Thyroid Research and Practice

ORIGINAL ARTICLE
Year
: 2012  |  Volume : 9  |  Issue : 1  |  Page : 7--8

Transplacental transfer of antithyroid antibodies a preliminary report


Sreekala Sreedharan1, Poulose K Poulose2, Lalitha Kesavan3, Kristin Indumathi3,  
1 Department of Obstetrics and Gynecology, SUT Hospital, Trivandrum, Kerala, India
2 Department of General Medicine, SUT Hospital, Trivandrum, Kerala, India
3 Department of Neonatology, SUT Hospital, Trivandrum, Kerala, India

Correspondence Address:
Poulose K Poulose
Department of General Medicine, SUT Hospital, Trivandrum- 4, Kerala
India

Abstract

Maternal hypothyroidism can affect the fetus in the antenatal period or later in life, but the role of maternal thyroid antibodies in hypothyroidism in the offspring is not well understood. Since thyroid autoantibodies can damage the thyroid gland, those with antibodies have a greater chance of developing thyroid dysfunction in future. The aim of the present prospective study was to estimate the occurrence of transplacental transfer of maternal antithyroid antibodies to the offspring and to study its immediate consequence to the offspring«SQ»s thyroid function. TSH and antithyroid antibodies estimations of 20 offsprings of the hypothyroid and antithyroid-antibody-positive mothers were done. A high prevalence of either or both antithyroid antibodies (75%) was found in the offsprings of the antibody positive hypothyroid mothers though neonatal hypothyroidism was rare (5%). Only periodic follow-up of these children would reveal the importance of these antibodies in the neonatal period.



How to cite this article:
Sreedharan S, Poulose PK, Kesavan L, Indumathi K. Transplacental transfer of antithyroid antibodies a preliminary report.Thyroid Res Pract 2012;9:7-8


How to cite this URL:
Sreedharan S, Poulose PK, Kesavan L, Indumathi K. Transplacental transfer of antithyroid antibodies a preliminary report. Thyroid Res Pract [serial online] 2012 [cited 2022 Aug 18 ];9:7-8
Available from: https://www.thetrp.net/text.asp?2012/9/1/7/92388


Full Text

 Introduction



Maternal hypothyroidism is a relatively common condition. This may be due to autoimmune thyroid disease in many cases. These women will have positive thyroid antibodies namely thyroid peroxidase antibody (TPO) and antithyroglobulin antibody (ATG) of which the former is more common. Previous studies done by us showed prevalence of thyroid autoantibodies in 29% of pregnant patients and hypothyroidism in 5.4% of patients with positive antibodies. [1]

Autoimmune hypothyroidism in three successive generations in the same family and also in many members of the same family is not rare. We have also reported very high prevalence of thyroid autoantibodies in asymptomatic young females. [2] Maternal hypothyroidism can affect the fetus in the antenatal period or later in life, but the role of maternal thyroid antibodies in hypothyroidism in the offspring is not well understood. Autoimmune thyroiditis can be due to genetic or environmental factors and may be mediated by cellular or humoral immunity. The frequency of diagnosis of autoimmune thyroiditis is higher now, probably because of the increased awareness among doctors and availability of facilities for estimating the antibodies. [3]

 Materials and Methods



Hypothyroid mothers with elevated levels of ATG and/or TPO seen at the antenatal OPD at SUT Hospital, Trivandrum, were followed up through pregnancy and delivery. Hypothyroid mothers with normal levels of the antibodies were excluded from the study. Three days after delivery, the thyroid function of the neonates was studied including the presence of antimicrosomal antibodies and antithyroglobulin antibodies. TSH was estimated using the ELISA test and antibody levels using the chemiluminescent method.

 Results



There were 20 mothers who were diagnosed as hypothyroid and found to have either or both of the antibodies positive. All of them were on thyroxine supplements and euthyroid at the time of the study. Duration of hypothyroidism varied from 3 months to 12 years and dose of thyroxine from 25 to 150 μg per day. Only one subject had a positive family history of hypothyroidism in a first-degree relative.

Of the 20 women, 17 had positive TPO, i.e., 85%, and 8 were ATG positive, i.e., 40%. Both TPO and ATG were found to be positive in 5, i.e., 25% [Table 1].{Table 1}

Of the 17 TPO positive women, 13 had high TPO levels in their newborns, i.e., 76%, and among the 8 ATG positive women 5 babies had high ATG levels, i.e., 63% .Out of a total of 20 babies 15 had TPO and/or ATG abnormal (75%). Out of these, 4 had both TPO and ATG elevated and 1 had only ATG abnormal while TPO alone was high in 10. All except one baby had euthyroid values. This baby had a borderline high value of TSH but T4 was normal and TPO was positive. In three mothers with only positive ATG, one offspring had both antibodies positive and one had only ATG positive, whereas in two cases with both antibodies positive, the offspring showed only positive TPO [Table 2].{Table 2}

 Discussion



It is well known that thyroid autoantibodies can damage the thyroid gland and suppress its function and those with antibodies have a greater chance of developing thyroid dysfunction in future. Hence, we wanted to study the presence of thyroid autoantibodies in the neonates of those mothers with positive antibodies.

We found a high prevalence of antithyroid antibodies in the babies of mothers born to hypothyroid mothers with positive antithyroid antibodies. Though congenital hypothyroidism was not detected, whether these antibodies would affect the newborn's thyroid function remains to be seen. There have been reports of both subtle thyroid abnormalities in the newborns due to transplacental antibodies and no effect for these antibodies. [4],[5],[6],[7],[8] Whether these antibodies would persist in the babies or is a transient phenomenon is also not yet known. We found persistence of these antibodies in two babies even after 6 months. The relation between the presence of thyroid antibodies and later development of thyroid dysfunction needs to be examined further.

This is only a preliminary study and unless we do a longitudinal study of these children, the relevance of the presence of thyroid antibodies in them cannot be properly understood. Hence periodic follow-up of these children by estimating their TSH and antibody levels is being planned.

References

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